Offset mechanism for printing-machines.



H. M. BARBER.

OPILSBT MECHANISM FOR PRINTING MACHINES.

APPLIOATION FILED MAY 21, 190B.

Patented July 4, 1911;

2 SHEETS-SHEET 1.

H. M. BARBER.

0mm MECHANISM FOR PRINTING MACHINES.

APPLICATION FILED MAY 21, 1908. 996,902, Patented July 4,1911.

2 SHEETS-SHEET 2.

rrn sA'r ran'r are HOWARD M. BARBER, OF STONINGTON, CONNECTICUT,ASSIGNOR T0 C. B. COTTRELL & SONS COMPANY, OF NEW YORK, N. Y., ACORPORATION OF NEW JERSEY.

OFFSET MECHANISM FOR PRINTING-MACHINES.

Specification of Letters Patent.

Application filed May 21, 1908.

Patented July 4, 1911. Serial No. 434,129.

T 0 all whom it may concern:

Be it known that I, HOWARD M. BARBER, a citizen of the United States,and resident of Stonington, in the county of New London and State ofConnecticut, have invented a new and useful Improvement in OffsetMechanism for Printing-Machines, of which the following is aspecification.

My invention relates to an improvement in offset mechanism for printingmachines and has for its object to provide a tension adjusting devicefor the shifting tympan supply roller whereby the tension of the rollermay be accurately adjusted.

A practical embodiment of my invention is represented in theaccompanying drawings in which Figure 1 represents an end view of aportion of an impression cylinder with my improved tension adjustingdevice for the shifting tympan supply roller applied thereto, certain ofthe parts being broken away to more clearly show the partsbeneath them;Fig. 2 is a detail transverse section through a portion of theimpression cylinder; Fig. 3 is a view in side elevaton of the shiftingtympan supply roller journal and its tension adjusting device, a portionof the tension spring being bro-ken away to more clearly show theengagement of the tension adjust ing cap with the ournal of the tympansupply roller; Fig. 4 is an end view of the same with the tensionadjusting cap and the tension spring removed; Fig. 5 is an end View ofthe tension spring; Fig. 6 is an in ner end view of the tensionadjusting cap; and Fig. 7 is a side view of the same.

The impression cylinder is denoted by 1 and its shaft by 2. The tympansupply roll 3 is wound upon the roller 4 and the 'tympan runs from saidroller to the exterior of the cylinder through an opening 5 and fromthence over the impression surface of the cylinder to another opening 6where it passes into the interior of the cylinder and is engaged by thefeed rollers 7 and 8, from whence it is wound upon the take-up roller 9.The usual blankets 10 are interposed between the surface of the roll anda tympan along the impression surface of the cylinder.

The mechanism for shift-ing the tympan at predetermined intervals iswell known in the art and will therefore not be particularly describedherein, the present invention being devoted exclusively to the tensionadjusting device for the tympan supply roller.

The journal 11 of the tympan supply roller 4 extends outside of theimpression cylinder 1 and is there provided with a ratchet wheel 12having a limited rotary movement with respect to the said journal. Thislimited rotary movement in the present instance is.

The feed rollers 7 and 8 are geared to- I gether and they, as well asthe take-up roller 9, are positively rotated at the 'desired intervalsfor shifting the tympan to present a clean portion on the impressionsurface of the cylinder.

In order to prevent the stoppage of the supply roller 4 by the pawllever 15 before the stoppage of the feed rollers 7, 8, and theconsequent tearing of the tympan, the ratchet wheel 12 has a limitedrotary yielding movement under spring tension on the journal 11 of thesupply roller 4, as follows. Between the said ratchet wheel 12 and thejournal 11, there is interposed a coil spring 20, the said spring havingone end secured to the said ratchet wheel by a pin 21 and its other endsecured to the tension adjusting cap 22 as, for instance, by providingthe cap with a transverse groove 23 arranged to receive the straightenedportion 24 of the outer end of said spring. This spring is so coiledthat when the ratchet wheel is locked by the teeth 16 of the pawl lever15, the spring will tend to turn the journal in a direction to wind orhold back the tympan on the supply roller 4 and the said ratchet wheeland pawl lever will thereby constitute a yielding stop to the tympan. Toadjust the tension of this spring to the utmostnicety so as to securethe proper effect upon the tympan, the tension adjusting cap 22 isarranged to be interlocked with the supply roller journal 11 indifferent rotary adjustments, as follows. The outer end of the journal11 is provided with an annular the end of the journal 11, the head ofwhich bolt serves'to lock the cap to the journal when the bolt isscrewed home. This bolt is of sufficient length so that when it isunscrewed a short distance, the cap 22 may be moved outwardly away fromthe outer end of the journal 11 a sufficient distance to permit a rotaryadjustment of the cap and thereby a tensional adjustment of the spring20. The bolt may then be screwed home for holding the spring in suchproper tensional adjustment.

What I claim is:

1. The combination with the impression cylinder, a shifting tympansupply roller therefor and its journal, of a ratchet wheel looselymounted on said journal, a tension cap, the adjacent ends of the tensioncap and journal being provided with annular series of teeth arranged tobe interlocked, means for securing the tension cap in its differentrotary adjustments with respect to the journal, and a tension springconnecting the ratchet wheel and tenslon cap.

Copies of this patent may be obtained for 2. The combination with theimpression cylinder, a shifting tympan supply roller therefor and itsjournal, of a ratchet wheel loosely mounted on said journal, a tensioncap arranged to be interlocked with the roller journal, a bolt having ascrew thread ed engagement with the journal for securing the tension capand journal in their interlocked adjustment and a tension springconnecting the ratchet wheel and tension cap.

3. The combination with the impression cylinder, a shifting tympansupply roller therefor and its journal, of a ratchet wheel looselymounted on said journal, a tension cap, the adjacent ends of the tensioncap and journal being provided with annular series of teeth arranged tobe interlocked, a bolt engaging the journal for securing the tension capin its diiierent rotary adjustments with respect to the journal and atension spring connecting the ratchet wheel and tension cap.

In testimony, that I claim the foregoing as my invention, I have signedmy name in presence of two Witnesses, this nineteenth day of May A. D.1908.

HOl/VARD M. BARBER.

Witnesses A. It. STILLMAN, ARTHUR M. CQTTRELL.

five cents each, by addressing the Commissioner of Patents, Washington,D. G.

